sfnt/ttload.c in FreeType before 2.5.4 proceeds with offset+length calculations without restricting the values, which allows remote attackers to cause a denial of service (integer overflow and out-of-bounds read) or possibly have unspecified other impact via a crafted SFNT table.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.